Patent Grant
9658581
Field
The present disclosure relates to an image heating apparatus, such as a fixing device mounted in an image forming apparatus including a copier and a printer employing an electrophotographic method or an electrostatic recording method, or a glossing device that improves a gloss of a toner image by reheating a fixed toner image on a recording material. Furthermore, the present disclosure relates to a heater used in the image heating apparatus.
Description of the Related Art
There is a device, serving as an image heating apparatus, including a cylindrical film, a heater that is in contact with an inner surface of the heater, and a roller that forms a nip portion together with the heater with the film in between. When small-sized sheets are continuously printed in the image forming apparatus in which the image heating apparatus is mounted, a phenomenon (a sheet non-passing portion temperature rise) in which temperature in the areas of the nip portion in a longitudinal direction where the sheets do not pass rises occurs. When the temperature of the sheet non-passing portion becomes excessively high, the parts inside the device may be damaged, and there may be cases in which, when a large-sized sheet is printed while the sheet non-passing portion temperature rise is occurring, the toner causes a high temperature offset to occur on the area of the film corresponding to the small-sized sheet non-passing portion.
As a technique of suppressing the sheet non-passing portion temperature rise from occurring, a device in which a heat generation resistor on a heater is divided into a plurality of groups (heat generating blocks) in the longitudinal direction of the heater so as to switch the heat distribution of the heater according to the size of the recording material has been proposed (Japanese Patent Laid-Open No. 2014-59508).
The sizes of the recording material used in the device are diverse and a heater that is capable of forming heat distributions that are suitable for various sheet size is in need.
The present disclosure provides a heater and an image heating apparatus that are capable of forming heat distributions suitable for a variety of sheet sizes.
The present disclosure provides a heater including a substrate, a first heat generating line provided on the substrate and in a longitudinal direction of the substrate, the first heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently, and a second heat generating line provided on the substrate and in the longitudinal direction of the substrate, the second heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently. In the heater, divided positions of the first heat generating line and divided positions of the second heat generating line are different in the longitudinal direction, and the first heat generating line and the second heat generating line are each configured such that an electric current flows in a heating element of the heat generating blocks of the first heat generating line and a heating element of the heat generating blocks in the second heat generating line in a direction that intersects the longitudinal direction.
Further features of aspects of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, referring to the drawings, modes to implement the present discloser will be exemplified in detail with the exemplary embodiments. Note that the dimensions, the materials, and the shapes of the components, the relative configuration of the components, and the like that are described in the following exemplary embodiments are to be appropriately altered based on the device to which the present disclosure is applied and on various conditions. In other words, the scope of the disclosure is not intended to be limited by the exemplary embodiments below.
Note that reference numeral 18 is a drum cleaner that cleans the photosensitive drum 19, and reference numeral 28 is a feed tray (a manual feed tray) including a pair of recording material restricting plate that are capable of width adjusting according to the size of the recording material P. The feed tray 28 is provided for coping with recording materials P with sizes other than the standard size. Reference numeral 29 is a pickup roller that feeds the recording material P from the feed tray 28, and reference numeral 30 is a motor that drives a roller 208 and the like in the fixing apparatus. Electric power is supplied to a heater 300 in the fixing apparatus 200 from a control circuit 400 serving as a heater driving unit. The photosensitive drum 19, the charge roller 16, the scanner unit 21, the developing roller 17, and the transfer roller 20 described above constitute an image forming unit that forms an unfixed image on the recording material P. Furthermore, in the present exemplary embodiment, the developing unit including the photosensitive drum 19, the charge roller 16, and the developing roller 17, and the cleaning unit including a drum cleaner 18 are configured as a process cartridge 15 that is detachable with respect to the main body of the image forming apparatus 100.
The image forming apparatus 100 of the present exemplary embodiment corresponds to a plurality of recording material sizes. Letter paper (215.9 mm×279.4 mm), legal paper (215.9 mm×355.6 mm), A4 paper (210 mm×297 mm), and executive paper (184.2 mm×266.7 mm) can be set in the sheet supplying cassette 11. Furthermore, JIS B5 paper (182 mm×257 mm), A5 paper (148 mm×210 mm), and the like can be set. Non-standard-sized sheets including a DL envelope (110 mm×220 mm) and a COM 10 envelope (about 105 mm×241 mm) can be fed from the feed tray 28 and can be printed.
The image forming apparatus 100 of the present exemplary embodiment basically performs a short edge feed of the sheets of paper (conveys the sheets of paper such that the long side thereof is parallel to the conveyance direction). In the command 100, the maximum sheet-passing width of the recording material P is 215.9 mm and the minimum sheet-passing width is 76.2 mm. Note that the printer of the present exemplary embodiment is a center-referring image forming apparatus that conveys the recording material while matching the center of the recording material in the width direction with a conveyance reference X set at the center of the heater in the longitudinal direction.
By receiving motive power from a motor 30, the pressure roller 208 rotates in an arrow R1 direction. By following the rotation of the rotating pressure roller 208, the fixing film 202 rotates in an arrow R2 direction. A fixing process is performed on the unfixed toner image on the recording material P by applying heat to the fixing film 202 while the recording material P is pinched and conveyed at the fixing nip portion N. A thermistor TH1, which is an example of a temperature detection member, abuts against the heater 300. Control of electric power to the heater 300 is performed on the basis of an output of the thermistor TH1 provided at about the middle of the heater 300 in the longitudinal direction. Furthermore, a safety element 212, such as a thermal switch or a thermal fuse, that is actuated by abnormal heat generation of the heater 300 and that cuts off the electric power supplied to the heater 300 also abuts against the heater 300.
The heater 300 includes a ceramic substrate 305, and heating elements 302a and 302b provided on the substrate 305. The heating element 302a and the heating element 302b are each configured such that application of power can be controlled independently. As described later, the heating element 302a is divided into three heat generating blocks in a longitudinal direction (a direction that is orthogonal to the conveyance direction of the recording material) of the heater 300, and is configured so that the heat generating area in the longitudinal direction can be switched in two stages. In a similar manner and as described later, the heating element 302b is divided into three heat generating blocks in the longitudinal direction of the heater 300, and is configured so that the heat generating area in the longitudinal direction can be switched in two stages. Since the divided positions of the heat generating blocks of the heating element 302a and the divided positions of the heat element 302b are different in the longitudinal direction of the heater 300, the heater 300 is configured so as to be capable of switching the heat generating area in the longitudinal direction in four stages.
The heater 300 includes the ceramic substrate 305, a sliding surface layer 1 that is a surface that comes into contact with the film 202, a back surface layer 1 that is provided on the substrate 305, and a back surface layer 2 that covers the back surface layer 1. The sliding surface layer 1 includes a surface protecting layer 308 formed by coating glass or polyimide. The back surface layer 1 includes conductors and heating elements. The back surface layer 2 includes an insulating (glass in the present exemplary embodiment) surface protecting layer 307.
The back surface layer 1 includes a conductor 301a and a conductor 301b serving as a conductor A provided in the longitudinal direction of the heater 300. The conductor 301b is disposed downstream in the conveyance direction of the recording material P with respect to the conductor 301a. Furthermore, the back surface layer 1 includes a conductor 303 (303-1, 301-2, and 303-3) serving as a conductor B provided parallel to the conductors 301a and 301b. The conductor B is provided between the conductor 301a and the conductor 301b and in the longitudinal direction of the heater 300.
Furthermore, the back surface layer 1 includes the heating element 302a (302a-1, 302a-2, and 302a-3) and the heating element 302b (302b-1, 302b-2, and 302b-3). The heating elements 302a and 302b are formed of a substance that has a positive resistance temperature characteristic. A positive resistance temperature characteristic is a characteristic in which the resistance value increases when the temperature increases. The heating element 302a is provided between the conductor 301a and the conductor 303, and generates heat by having power applied thereto through the conductor 301a and the conductor 303. The heating element 302b is provided between the conductor 301b and the conductor 303, and generates heat by having power applied thereto through the conductor 301b and the conductor 303.
A heating member constituted by the conductor 301a, the conductor 303, and the heating element 302a is divided into three heat generating blocks (BLa-1, BLa-2, and BLa-3) in the longitudinal direction of the heater 300. In other words, the heating element 302a is divided into three areas, namely, the heating elements 302a-1, 302a-2, and 302a-3 in the longitudinal direction of the heater 300. Furthermore, the conductor 303 connected to the heating element 302a is divided into three areas, namely, the conductor 303-1, 303-2, and 303-3, so as to correspond to the divided areas of the heating element 302a. A group constituted by the heating element 302a-1, the conductor 303-1, and the conductor 301a is referred to as a heat generating block BLa-1. Similarly, a group constituted by the heating element 302a-2, the conductor 303-2, and the conductor 301a is referred to as a heat generating block BLa-2. Furthermore, a group constituted by the heating element 302a-3, the conductor 303-3, and the conductor 301a is referred to as a heat generating block BLa-3. The three heat generating blocks BLa-1, BLa-2, and BLa-3 constitute a group a of heat generating blocks serving as a first heat generating line. As illustrated in
By connecting the electric contacts described later to the electrodes, each of the heat generating blocks in the group a of heat generating blocks can be controlled independently.
Similar to the group a of heat generating blocks, a heating member constituted by the conductor 301b, the conductor 303, and the heating element 302b is divided into three heat generating blocks (BLb-1, BLb-2, and BLb-3) in the longitudinal direction of the heater 300. In other words, the heating element 302b is divided into three areas, namely, the heating elements 302b-1, 302b-2, and 302b-3 in the longitudinal direction of the heater 300. Furthermore, the conductor 303 connected to the heating element 302b is divided into three areas, namely, the conductor 303-1, 303-2, and 303-3, so as to correspond to the divided areas of the heating element 302b. A group constituted by the heating element 302b-1, the conductor 303-1, and the conductor 301b is referred to as a heat generating block BLb-1. Similarly, a group constituted by the heating element 302b-2, the conductor 303-2, and the conductor 301b is referred to as a heat generating block BLb-2. Furthermore, a group constituted by the heating element 302b-3, the conductor 303-3, and the conductor 301b is referred to as a heat generating block BLb-3. The three heat generating blocks BLb-1, BLb-2, and BLb-3 constitute the group b of heat generating blocks serving as a second heat generating line. Each of the heat generating blocks in the group b of heat generating blocks can be controlled independently.
As described above, the first heat generating line that is divided into a plurality of heat generating blocks that are capable of being independently controlled with respect to each other in the longitudinal direction of the heater 300 is provided on the substrate 305 in the longitudinal direction of the heater 300 (in the longitudinal direction of the substrate 305). Furthermore, the second heat generating line that is divided into a plurality of heat generating blocks that are capable of being independently controlled with respect to each other in the longitudinal direction of the heater 300 is provided on the substrate 305 in the longitudinal direction of the heater 300.
Furthermore, the first heat generating line and the second heat generating line are configured such that in the plurality of heat generating blocks, heating elements are connected between the pair of conductors (the conductors A and B) provided in the longitudinal direction of the heater 300 so that an electric current flows in the heating elements in a direction that is orthogonal to the longitudinal direction of the heater 300.
Boundary positions between the heat generating blocks that constitute the group a of heat generating blocks and the heat generating blocks that constitute the group b of heat generating blocks are set in a bilaterally symmetrical manner with the conveyance reference X of the recording material P as the central axis. The boundary between the heat generating block BLa-1 and the heat generating block BLa-2, and the boundary between the heat generating block BLa-2 and the heat generating block BLa-3 are set at positions that are 78.5 mm in the left and right from the conveyance reference X. Accordingly, the heat generating area of the heat generating block BLa-2 is 157 mm in width extending 78.5 mm in the left and right from the conveyance reference X. Similarly, the boundary between the heat generating block BLb-1 and the heat generating block BLb-2, and the boundary between the heat generating block BLb-2 and the heat generating block BLb-3 are set at positions that are 57.5 mm in the left and right from the conveyance reference X. Accordingly, the heat generating area of the heat generating block BLb-2 is 115 mm in width extending 57.5 mm in the left and right from the conveyance reference X. Furthermore, the entire length of the group a of heat generating blocks is 220 mm. The entire length of the group b of heat generating blocks is 190 mm. As described above, the heat generating area of the entire first heat generating line in the longitudinal direction of the heater 300 is different from the heat generating area of the entire second heat generating line in the longitudinal direction of the heater 300.
As described above, the heat generating area of the entire first heat generating line in the longitudinal direction of the heater 300 is different from the heat generating area of the entire second heat generating line in the longitudinal direction of the heater 300. Furthermore, the divided positions of the first heat generating line and the divided positions of the second heat generating line are different. Accordingly, the heat distribution in the longitudinal direction of the heater 300 formed in one of the heat generating blocks in the first heat generating line is a heat distribution that cannot be formed by combining one, or two or more heat generating blocks in the second heat generating line. Furthermore, each of the heat generating blocks of the first heat generating line and each of the heat generating blocks of the second heat generating line are controlled according to information on the size and the like of the recording material. Control of the heater control circuit and that of each heat generating block will be described later.
As illustrated in
A method of connecting the electrodes to electric contacts C is illustrated in
A relay 440 is used as an electric power cut-off unit that cuts off supply of electric power to the heater when the temperature of the heater rises excessively due to malfunction or the like. The relay 440 is activated by an output from the thermistor TH1. When an RLON 440 signal turns high, a transistor 443 is turned on, power from a power source Vcc2 is applied to a coil on the secondary side of the relay 440, and a contact on a primary side of the relay 440 is turned on. When an RLON 440 signal turns low, the transistor 443 is turned off, current from the power source Vcc2 flowing to the coil on the secondary side of the relay 440 is cut off, and the contact on the primary side of the relay 440 is turned off. Note that a resistor 444 is a current limit resistor.
An operation of a safety circuit 445 using the relay 440 will be described. When a detection temperature (TH1 signal) of the thermistor TH1 exceeds a predetermined value, a comparing unit 441 operates a latching unit 442, and the latching unit 442 latches the RLOFF signal at a low state. Even if the CPU 420 turns the RLON 440 signal high when the RLOFF signal turns low, since the transistor 443 is kept off, the relay 440 is kept off (is kept in a safe state). Furthermore, electric power to the coil on the secondary side of the relay 440 is suppled through the safety element 212. Accordingly, when the temperature of the heater rises excessively due to malfunction or the like, the safety element 212 is actuated and the supply of electric power to the coil on the secondary side of the relay 440 is cut off, such that the contact on the primary side of the relay 440 is turned off. When the detection temperature of the thermistor TH1 does not exceed the predetermined value that has been set, the RLOFF signal of the latching unit 442 turns into an open state. Accordingly, when the CPU 420 turns the RLON 440 signal high, the relay 440 can be turned on and electric power can be supplied to the heater 300.
An operation of the switching relay 459 will be described. The switching relay 459 is disposed between the groups of heat generating blocks of the heater 300 and a triac 416 described later, and is capable of selecting to which of the group a of heat generating blocks and the group b of heat generating blocks power is to be applied. A contact 459a of the switching relay 459 is connected to the group a of heat generating blocks through the electrode E0a. A contact 459b of the switching relay 459 is connected to the group b of heat generating blocks through the electrode E0b. A contact 459c of the switching relay 459 is connected to the triac 416. The switching relay 459 operates according to an RLON 459 signal from the CPU 420 sent through a current limit resistor 479. When the RLON 459 signal turns high, a transistor 469 is turned on and the switching relay 459 connects the contacts 459a and 459c to each other. With the above, power can be applied to the group a of heat generating blocks from the triac 416. On the other hand, when the RLON 459 signal turns low, the transistor 469 is turned off and the switching relay 459 connects the contacts 459b and 459c to each other. With the above, power can be applied to the group b of heat generating blocks from the triac 416.
An operation of the relay 451 will be described. The relay 451 operates according to an RLON 451 signal from the CPU 420. When the RLON 451 signal turns high, a transistor 461 is turned on, power from the power source Vcc2 is applied to a coil on the secondary side of the relay 451, and a contact on a primary side of the relay 451 is turned on. When the RLON 451 signal turns low, the transistor 461 is turned off, current from the power source Vcc2 flowing to the coil on the secondary side of the relay 451 is cut off, and the contact on the primary side of the relay 451 is turned off. Note that a resistor 471 is a current limit resistor. In the present exemplary embodiment, by controlling the relay 451, selection of whether to supply electric power to the heat generating block BLa-2 (or BLb-2) or to the heat generating blocks BLa-1 to BLa-3 (or BLb-1 to BLb-3) can be made. As described above, the relay 459 is a relay for selecting the first heat generating line or the second heat generating line, and the relay 451 is a relay for selecting the heat generating area in the longitudinal direction of the heater 300.
An operation of a driving circuit of the triac 416 will be described. Resistors 413 and 417 are bias resistors for the triac 416, and a phototriac coupler 415 is a device for obtaining a creepage distance between the primary and the secondary. Furthermore, by applying power to a light emitting diode of the phototriac coupler 415, the triac 416 is turned on. A resistor 418 is a resistor for limiting the electric current flowing from a power source Vcc to the light emitting diode of the phototriac coupler 415, and the phototriac coupler 415 is turned on and off with a transistor 419. The transistor 419 operates according to a FUSER 1 signal from the CPU 420 sent through a current limit resistor 412.
A method of controlling the temperature of the heater 300 will be described. In the present exemplary embodiment, control of the temperature of the heater 300 is performed based on the heater temperature detected by the thermistor TH1. A voltage signal according to the temperature of the thermistor TH1 is input to the CPU 420. With the above, the CPU 420 detects the temperature according to the signal TH1. In the internal processing of the CPU (a control unit) 420, the electric power that is to be supplied is calculated, for example, through PI control, on the basis of the detection temperature of the thermistor TH1 and a set temperature of the heater 300. Furthermore, conversion to a control level of a phase angle (phase control), a wavenumber (wavenumber control) that correspond to the supplied electric power is performed and the triac 416 is controlled with the above control condition.
The control circuit 400 of the present exemplary embodiment is capable of selecting the heat generating area (the heat generating width) in four stages by controlling the relay 451 and the switching relay 459 according to width information of the recording material (or width information of the image forming area) input to the CPU 420. Referring to table 1, the relationship between the control states of the relay 451 and the switching relay 459, and the heat generating area of the heater in the longitudinal direction will be described.
When the switching relay 459 is connected to the group b of heat generating blocks (RLON 459 signal is low) and the relay 451 is off (RLON 451 signal is low), power can be applied to the heat generating block BLb-2. With the above, heat is generated in the width of 115 mm illustrated in
As described above, the control circuit 400 of the present exemplary embodiment is capable of selecting the heat generating area (the heat generating width) in four stages according to the width information of the recording material P (or width information of the image forming area). Accordingly, generation of heat in the area of the heater 300 where the recording material P does not pass can be suppressed effectively. Furthermore, in the heater 300 of the present example, the electrodes E1 to E3 are common between the heating elements in the first heat generating line and the heating elements in the second heat generating line. Accordingly, the number of electrodes can be reduced advantageously.
Note that instead of a configuration that switches the destination of connection of the triac 416 with the switching relay 459, even when two triacs are connected to each of the group a of heat generating blocks and the group b of heat generating blocks, a similar advantageous effect as that of the first exemplary embodiment can be obtained.
A second exemplary embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of the second exemplary embodiment are the same as those of the first exemplary embodiment. Accordingly, elements and configurations that have the same or corresponding functions as those of the first exemplary embodiment will be attached with the same reference numerals and detailed description thereof will be omitted. Matters that are not particularly described in the second exemplary embodiment is similar to those of the first exemplary embodiment.
Referring to
The back surface layer 1 of the heater 800 includes a conductor 803a (803a-1 to 803a-5) and a conductor 803b that serve as the conductor B provided in the longitudinal direction of the heater 800. The conductor 803b is disposed downstream in the conveyance direction of the recording material P with respect to the conductor 803a. Furthermore, the back surface layer 1 includes a conductor 801 serving as a conductor A that is provided parallel to the conductors 803a and 803b. The conductor 801 is provided between the conductor 803a and the conductor 803b and in the longitudinal direction of the heater 800.
Furthermore, the back surface layer 1 includes a heating element 802a (802a-1 to 802a-5) and a heating element 802b. The heating elements 802a and 802b have a positive resistance temperature characteristic. The heating element 802a is provided between the conductor 801 and the conductor 803a, and generates heat by having electric power supplied thereto through the conductor 801 and the conductor 803a. The heating element 802b is provided between the conductor 801 and the conductor 803b, and generates heat by having electric power supplied thereto through the conductor 801 and the conductor 803b.
Similar to the first exemplary embodiment, a heating member constituted by the conductor 801, the conductor 803a, and the heating element 802a is divided in the longitudinal direction of the heater 800. In the second exemplary embodiment, the heating member is divided into five heat generating blocks (BLa-1 to BLa-5). In other words, the heat generating block BLa-3 including the heating element 802a-3 and a pair of conductors 803a-3 and 801 is provided in an area including the conveyance reference X. Furthermore, the heat generating blocks BLa-1, BLa-2, BLa-4, and BLa-5 including pairs including the heating elements 802a-1, 802a-2, 802a-4, and 802a-5 and the conductors 803a-1, 803a-2, 803a-4, and 803a-5, respectively, and the conductor 801 are provided. The five heat generating blocks BLa-1 to BLa-5 constitute the group a of heat generating blocks serving as the first heat generating line. Furthermore, although the second heat generating line is a single heat generating block BLb constituted by the conductor 801, the conductor 803b, and the heating element 802b, the second heat generating line will be referred to as the group b of heat generating blocks.
Boundary positions between the heat generating blocks that constitute the group a of heat generating blocks are set in a bilaterally symmetrical manner with the conveyance reference X of the recording material P as the central axis. In other words, the boundary between the heat generating block BLa-1 and the heat generating block BLa-2, and the boundary between the heat generating block BLa-4 and the heat generating block BLa-5 are set at positions that are 78.5 mm in the left and right from the conveyance reference X. Furthermore, the boundary between the heat generating blocks BLa-2 and BLa-3, and the boundary between the heat generating blocks BLa-3 and BLa-4 are set at positions that are 57.5 mm in the left and right from the conveyance reference X. The entire length of the group a of heat generating blocks is 220 mm. Furthermore, the entire length of the heat generating block BLb is 190 mm.
The heater 800 is provided with electrodes E0, Ea-1, Ea-2, Ea-3, Ea-4, Ea-5, and Eb. The electrode E0 is an electrode for supplying electric power to the group a of heat generating blocks and the heat generating block BLb through the conductor 801. The electrodes Ea-1 to Ea-5 are electrodes for supplying electric power to the heat generating blocks BLa-1 to BLa-5, respectively, through the conductors 803a-1 to 803a-5, respectively. The electrode Eb is an electrode for supplying electric power to the heat generating block BLb through the conductor 803b.
The surface protecting layer 307 constituting the back surface layer 2 is formed at a portion other than the portions of the electrodes E0, Ea-1 to Ea-5, and Eb. Accordingly, electric contacts C for supplying electric power can be connected to each electrode from the back surface side of the heater 800. Feeding cables are connected to the electric contacts C for supplying electric power from a control circuit 900 described later.
Referring to
Referring to table 2, the relationship between the control states of the relays 951 and 952 and the triacs 916a and 916b, and the heat generating area of the heater 800 in the longitudinal direction will be described.
When the triac 916b is off and the relays 951 and 952 are both off, power can be applied to only the heat generating block BLa-3. With the above, heat is generated in the width of 115 mm illustrated in
As described above, the control circuit 900 of the present exemplary embodiment is capable of selecting the heat generating area (the heat generating width) according to the width information of the recording material P (or width information of the image forming area). Accordingly, generation of heat in the area of the heater 800 where the recording material P does not pass can be suppressed effectively.
A third exemplary embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of the third exemplary embodiment are the same as those of the first exemplary embodiment. Accordingly, elements and configurations that have the same or corresponding functions as those of the first exemplary embodiment will be attached with the same reference numerals and detailed description thereof will be omitted. Matters that are not particularly described in the third exemplary embodiment is similar to those of the first exemplary embodiment.
Referring to
The back surface layer 1 of the heater 500 includes a conductor 503a (503a-1, 503a-2, and 503a-3) and a conductor 503b (503b-1, 503b-2, and 503b-3) that serve as the conductor B provided in the longitudinal direction of the heater 500. The conductor 503b is disposed downstream in the conveyance direction of the recording material P with respect to the conductor 503a. Furthermore, the back surface layer 1 includes a conductor 501 serving as a conductor A that is provided parallel to the conductors 503a and 503b. The conductor 501 is provided between the conductor 503a and the conductor 503b and in the longitudinal direction of the heater 500.
Furthermore, the back surface layer 1 includes a heating element 502a (502a-1, 502a-2, and 502a-3) and a heating element 502b (502b-1, 502b-2, and 502b-3). The heating elements 502a and 502b have a positive resistance temperature characteristic. The heating element 502a is provided between the conductor 501 and the conductor 503a, and generates heat by having electric power supplied thereto through the conductor 501 and the conductor 503a. The heating element 502b is provided between the conductor 501 and the conductor 503b, and generates heat by having electric power supplied thereto through the conductor 501 and the conductor 503b.
Similar to the first exemplary embodiment, the heating member constituted by the conductor 501, the conductor 503a, and the heating element 502a is divided into three heat generating blocks (BLa-1, BLa-2, and BLa-3) in the longitudinal direction of the heater 500. The three heat generating blocks BLa-1, BLa-2, and BLa-3 constitute the group a of the heat generating blocks serving as the first heat generating line. Similar to the first exemplary embodiment, the heating member constituted by the conductor 501, the conductor 503b, and the heating element 502b is divided into three heat generating blocks (BLb-1, BLb-2, and BLb-3) in the longitudinal direction of the heater 500. The three heat generating blocks BLb-1, BLb-2, and BLb-3 constitute the group b of heat generating blocks serving as the second heat generating line.
The divided positions of the group a of heat generating blocks and the group b of heat generating blocks in the longitudinal direction, and the entire length of each of the groups of heat generating blocks are set the same as those of the first exemplary embodiment. Furthermore, the group a of heat generating blocks and the group b of heat generating blocks set the conductor 501 serving as the conductor A as a common conductive path.
The heater 500 is provided with electrodes E0, Ea-1, Ea-2, Ea-3, Eb-1, Eb-2, and Eb-3. The electrode E0 is an electrode for supplying electric power to the group a of heat generating blocks and the group b of heat generating blocks through the conductor 501. The electrode Ea-1 is an electrode for supplying electric power to the heat generating block BLa-1 through the conductor 503a-1. The electrode Ea-2 is an electrode for supplying electric power to the heat generating block BLa-2 through the conductor 503a-2. The electrode Ea-3 is an electrode for supplying electric power to the heat generating block BLa-3 through the conductor 503a-3. The electrode Eb-1 is an electrode for supplying electric power to the heat generating block BLb-1 through the conductor 503b-1. The electrode Eb-2 is an electrode for supplying electric power to the heat generating block BLb-2 through the conductor 503b-2. The electrode Eb-3 is an electrode for supplying electric power to the heat generating block BLb-3 through the conductor 503b-3.
The surface protecting layer 307 constituting the back surface layer 2 is formed at a portion other than the portions of the electrodes E0, Ea-1, Ea-2, Ea-3, Eb-1, Eb-2, and Eb-3. Accordingly, electric contacts C for supplying electric power can be connected to each electrode from the back surface side of the heater 500. Feeding cables are connected to the electric contacts C for supplying electric power from a control circuit 600 described later.
Referring to
Referring to table 3, the relationship between the control states of the relays 651 and 652 and the triacs 616a and 616b, and the heat generating area of the heater in the longitudinal direction will be described.
When the triac 616a is off and the relay 652 is off, power can be applied to only the heat generating block BLb-2. With the above, heat is generated in the width of 115 mm illustrated in
As described above, the control circuit 600 of the present exemplary embodiment is capable of selecting the heat generating area (the heat generating width) according to the width information of the recording material P (or width information of the image forming area). Accordingly, generation of heat in the area of the heater 500 where the recording material P does not pass can be suppressed effectively.
A fourth exemplary embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of the fourth exemplary embodiment are the same as those of the third exemplary embodiment. Accordingly, elements and configurations that have the same or corresponding functions as those of the third exemplary embodiment will be attached with the same reference numerals and detailed description thereof will be omitted. Matters that are not particularly described in the fourth exemplary embodiment is similar to those of the third exemplary embodiment.
Referring to
The heater 700 of the fourth exemplary embodiment includes a conductor 701 serving as the conductor A. The conductor 701 is provided in the longitudinal direction of the heater 700, and is divided into a conductor 701a that is disposed on the upstream side in the conveyance direction of the recording material P, and a conductor 701b that is disposed on the downstream side in the conveyance direction of the recording material P. A conductor 703 serving as the conductor B is provided between the conductor 701a and the conductor 701b. The conductor 703 is provided in the longitudinal direction of the heater 700 and is divided into a conductor 703a (703a-1 to 703a-3) and a conductor 703b (703b-1 to 703b-3) in a short direction of the heater 700.
A heating element 702a (702a-1 to 702a-3) is provided between the conductors 701a and 703a and generates heat by having electric power supplied thereto through the conductor 701a and the conductor 703a. A heating element 702b (702b-1 to 702b-3) is provided between the conductors 701b and 703b and generates heat by having electric power supplied thereto through the conductor 701b and the conductor 703b.
Similar to the third exemplary embodiment, the heating member constituted by the conductor 701a, the conductor 703a, and the heating element 702a is divided into three heat generating blocks (BLa-1, BLa-2, and BLa-3) in the longitudinal direction of the heater 700. The three heat generating blocks BLa-1, BLa-2, and BLa-3 constitute the group a of the heat generating blocks serving as the first heat generating line. Similar to the third exemplary embodiment, the heating member constituted by the conductor 701b, the conductor 703b, and the heating element 702b is divided into three heat generating blocks (BLb-1, BLb-2, and BLb-3) in the longitudinal direction of the heater 700. The three heat generating blocks BLb-1, BLb-2, and BLb-3 constitute the group b of heat generating blocks serving as the second heat generating line.
The divided positions of the group a of heat generating blocks and the group b of heat generating blocks in the longitudinal direction, and the entire length of each of the groups of heat generating blocks are set the same as those of the third exemplary embodiment.
The heater 700 is provided with electrodes E0, Ea-1, Ea-2, Ea-3, Eb-1, Eb-2, and Eb-3. The electrode E0 is an electrode for supplying electric power to the group a of heat generating blocks and the group b of heat generating blocks through the conductor 701. The electrode Ea-1 is an electrode for supplying electric power to the heat generating block BLa-1 through the conductor 703a-1. The electrode Ea-2 is an electrode for supplying electric power to the heat generating block BLa-2 through the conductor 703a-2. The electrode Ea-3 is an electrode for supplying electric power to the heat generating block BLa-3 through the conductor 703a-3. The electrode Eb-1 is an electrode for supplying electric power to the heat generating block BLb-1 through the conductor 703b-1. The electrode Eb-2 is an electrode for supplying electric power to the heat generating block BLb-2 through the conductor 703b-2. The electrode Eb-3 is an electrode for supplying electric power to the heat generating block BLb-3 through the conductor 703b-3. Similar to the third exemplary embodiment, the feeding cables are connected to the electrodes through the electric contacts C.
The heater 700 of the fourth exemplary embodiment is capable of controlling heat generation by using the control circuit 600 of the third exemplary embodiment. Similar to the third exemplary embodiment, the heat generating area (the heat generating width) can be selected according to the width information of the recording material P (or the width direction of the image forming area), and temperature rise in the sheet non-passing portion can be suppressed in a variety of sheet sizes.
The present disclosure is not limited to the number of divisions of the heat generating block illustrated in the first to fourth exemplary embodiments. Furthermore, there may be three or more heat generating lines (groups of heat generating blocks).
Furthermore, in the first to fourth exemplary embodiment, the entire length of the group a of heat generating blocks and that of the group b of heat generating blocks are not the same; however, the entire lengths may be made the same. For example, as illustrated in
Furthermore, in the first to fourth exemplary embodiments, regarding the application of power to the group a of heat generating blocks and the group b of heat generating blocks, description has been given of a method of applying power to either one of the group a of heat generating blocks and the group b of heat generating blocks. However, a control method may be adopted in which the group a of heat generating blocks and the group b of heat generating blocks are configured to generate heat at the same time by setting a power application ratio between the group a of heat generating blocks and the group b of heat generating blocks. In such a case, a configuration such as the control circuit 600 in which a triac is connected to each of the group a of heat generating blocks and the group b of heat generating blocks is needed.
While aspects of the present invention have been described with reference to exemplary embodiments, it is to be understood that the aspects of the invention are not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2015-181135, filed Sep. 14, 2015, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-181135 | Sep 2015 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8471178 | Taniguchi | Jun 2013 | B2 |
| 8552342 | Sakakibara | Oct 2013 | B2 |
| 8592726 | Tsuruya | Nov 2013 | B2 |
| 9095003 | Sakakibara | Jul 2015 | B2 |
| 9098035 | Nakahara | Aug 2015 | B2 |
| 9445457 | Sakakibara | Sep 2016 | B2 |
| 9494899 | Nakahara | Nov 2016 | B2 |
| 20110062140 | Sakakibara | Mar 2011 | A1 |
| 20120121306 | Shimura | May 2012 | A1 |
| 20120201581 | Shimura | Aug 2012 | A1 |
| 20120201582 | Shimura | Aug 2012 | A1 |
| 20120308280 | Tsuruya | Dec 2012 | A1 |
| 20130251428 | Ueno | Sep 2013 | A1 |
| 20130299480 | Kakubari | Nov 2013 | A1 |
| 20130343790 | Shimura | Dec 2013 | A1 |
| 20130343791 | Shimura | Dec 2013 | A1 |
| 20140003848 | Sakakibara | Jan 2014 | A1 |
| 20140076878 | Shimura | Mar 2014 | A1 |
| 20140169845 | Nakahara | Jun 2014 | A1 |
| 20150289317 | Sakakibara | Oct 2015 | A1 |
| 20150293483 | Nakahara | Oct 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 2001-43956 | Feb 2001 | JP |
| 2010-54846 | Mar 2010 | JP |
| 2014-59508 | Apr 2014 | JP |
| 2014-153480 | Aug 2014 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20170075266 A1 | Mar 2017 | US |
